Homework 5 (Due: Nov. 14, 2005)

Purine Metabolism

1. Identify the key steps and describe the regulation of purine biosynthesis.

2. Describe the purpose of the salvage pathway and the role of HGPRT.

3. Identify the steps in purine degradation and the product of this process.

4. Discuss the causes of the defects associated with Gout and Lesch-Nyhan Syndrome.

Pyrimidine Metabolism

1. Identify the key steps and describe the regulation of pyrimidine biosynthesis.

2. Distinguish between the two forms of carbamoyl phosphate synthetase.

3. Identify the products of pyrimidine degradation .

4. Discuss the role of ribonucleotide reductase in the synthesis of deoxyribonucleotides.

5. Describe the role of thymidylate synthetase in nucleotide biosynthesis together with the function of folic acid.

6. Discuss the significance of chemotherapeutic agents (i.e. fluorouracil, methotrexate, deoxycoformycin, arabinoside-adenosine) in relation to nucleic acid synthesis.

DNA Synthesis

1. Define conservative and semiconservative replication.

2. Explain the difference between uni- and bi-directional replication.

3. List the differences and the similarities between leading and lagging strand synthesis.

4. Define the terms primer and template.

5. List the major eukaryotic DNA polymerases and state their function(s).

6. List the cis- and trans- acting factors required for initiating and sustaining DNA replication.

7. Describe how leading and lagging strand synthesis are coordinated.

8. State the function of Telomerase and describe its "probable" mechanism.

9. List some examples of drugs that inhibit replication and explain how they "inhibit" replication.

DNA Mutation and Repair

1. Define the following mutations: point, silent, missense, nonsense and frameshift.

2. Define the terms transition and transversion.

3. Describe what is meant by a conservative and nonconservative mutation.

4. List five major ways that DNA can be damaged or mutated.

5. Outline the major steps of mismatch , nucleotide excision and recombination repair.

6. Outline the pathway by whichp53 is believed to regulate DNA repair.

7. List four diseases that are attributed to defects in DNA repair.

RNA Synthesis and Processing

1. List the various types of RNA polymerases and their subunit compositions.

2. State the effects of a amanitin and rifampicin on transcription.

3. List the three phases of transcription and briefly describe the key aspects of each phase.

4. Define the function of a promoter, list the major characteristics of prokaryotic promoter, RNA polymerase I, RNA polymerase II, and RNA polymerase III promoters.

5. List the major types of initiation factors required for prokaryotic and eukaryotic transcription.

6. Outline the major steps in the processing of hnRNA, precursor rRNA and precursor tRNA.

© Dr. Noel Sturm 2005